1. Field of the Invention
This invention relates to a non-woven fabric. More particularly it relates to a non-woven fabric of hot-melt-adhesive composite fibers having a small weight per unit area thereof.
2. Description of the Prior Art
Non-woven fabrics obtained by using composite fibers composed of composite components of fiberformable polymers having different melting points from one another (hereinafter often referred to as hot-melt-adhesive composite fibers) have been known (see Japanese patent publication Nos. Sho 42-21318/1967, Sho 44-22547/1969, Sho 52-12830/1977, etc.). In recent years, the performance level of non-woven fabrics required therefor has also been more and more elevated, with the variety of the application fields of non-woven fabrics, and it has been basically required for non-woven fabrics to have a weight of non-woven fabric as small as possible and yet retain a strength of non-woven fabric as high as possible, and also exhibit a feeling as soft as possible. However, according to the above-mentioned known processes wherein composite fibers composed of composite components having different melting points from one another are merely used, it has been impossible to satisfy the above-mentioned requirements.
In order to obtain a non-woven fabric having a weight of non-woven fabric as small as possible and yet retaining a strength of non-woven fabric as high as possible, and also exhibiting a feeling as soft as possible, necessary conditions therefor are as follows:
(1) the non-woven fabric is composed of hot-melt-adhesive composite fibers of fine denier; and
(2) the lower melting component of hot-melt-adhesive composite fibers contributing to hot-melt-adhesion is soft and has a small and soft area of hot-melt-adhesion points. The soft feeling referred to herein means a soft and elastic feeling as represented by gauze.
The lower melting component of hot-melt-adhesive composite fibers so far used for constituting non-woven fabrics of hot-melt-adhesive composite fibers is polyethylene, and polyethylene used in the form of fibers is usually medium density or high density polyethylene, but these polyethylenes have a drawback that they have a high rigidity so that non-woven fabrics obtained therefrom are liable to exhibit a hard feeling. On the other hand, low density polyethylene has a low rigidity so that a soft feeling can be expected from non-woven fabrics obtained from the polyethylene, but it has an inferior spinnability and stretchability so that only thick fibers can be obtained; hence it is the present status that the expected soft feeling could not have been realized.
The object of the present invention is to provide a non-woven fabric of hot-melt-adhesive composite fibers without the above-mentioned drawbacks of conventional polyethylene, having a small weight per unit area thereof and hence a soft feeling.